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2 -Sheets-Sheet 1 F. A. HOWARD ET AL METHOD OF AND APPARATUS FORPREVENTING KNOGKING Original Filed Jan. '7. 1922 IN INTERNAL COMBUSTIONENGINES July 10, 1928.

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'Fl A. HOWARD ET ALI" METHOD OF AND APPARATUS, FOR PREVENTING KNOCKINGlIN INTERNAL GOMBUSTION ENGINES Original Filed Jan, '7. 19,22 2Sheets-Sheet 2 l J l X i i ,f l 1 --fj E l ff' i l l I i l l y l, g//iI;

.a .6 f ."7 g .a 9 1'@ 0% l/ L/ l Patented July 10, 1928.

`UNITED STATES `PATENT OFFICE,

FRANK A.. HOWARD, OF ELIZABETH, NEW JERSEY, AND THOMAS R. PARKER, OF

NEW YORK, N. Y., ASSIGNORS TO STANDARD DEVELOPMENT COMPANY, A CORPORA-TION OF DELAWARE.

METHOD 0F AND APPARATUS FOR PBEVENTING KNOCKING IN INTERNAL-COMBUSTIONENGINES.

Application led January 7, 1922, Serial This invention relates to amethod of and apparatus for preventing knocking in an internalcombustion engine and is particularly adapted to be used on variablespeed, variable load engines, such as automobile engines.

Engine designers have long known that it would be advantageous in manyways to use an engine having a much higher compression ratio than thosecommonly employed. This would make the engine much more eiicient byallowing it to run with a higher degree of compression at its normalworking loads such as are ordinarily encountered when running on thelevel, thereby effectinga great saving of fuel. This increasedcompression, however, has not been considered feasible due to thedetonation, or knocking77 as it is commonly called, of the ordinarymotor fuels at high compression.

This tendency of the engine to knock varies with the design andconditionof the engine and with the kind of fuel. For eX- ample, with any givenfuel, the degree of compression at which knocking begins depends uponthe shape of the cylinder, the location and number of spark plugs, thelocation of the valves, the temperature of the cylinder walls and theamount and location of the carbon deposit on the cylinder walls.

With the ordinary water-cooled engine using commercial gasoline,knocking begins at about a four to one compression while. with ethylalcohol it is not yet felt at ten to one compression, depending onengine conditions as previously explained.

Referring now to the drawings, Figure 1 is a vertical section through acarbureter embodying this invention; and Figure 2 is a graph showing theoperation of the carbureter. v

The carbureter consists of a body 10 having a mixing passagevll, aventuri V12 and an inlet 13 communicating with the atmosphere. Two fueljets 141- and 15 are arranged to deliver into the venturi 12 and theseare supplied with fuel from the float chambers 16 and 17 in a well knownmanner. A low compression fuel A such as gasoline or kero- No. 527,666.YRenewed January 5, 1928.

sene is fed to the float chamber 16 and thence to the jet 14. A highcompression fuel B such as alcohol or a fuel containing a knockpreventing substance as aniline is fed through the iioat chamber 17 tothe nozzle 15.

Needle valves 18 and 19 control the jets or nozzles 1st and 15 and areslidably mounted at the upper ends in a guide 20. These valves areconnected to a rocker arm 21 which is secured on a shaft 22 whichisjournalled in the walls vof the mixing chamber 11. The taper of thevalve points is carefully determined so that at any position of therocker arm the fuel supplied from one j et or the other or both will bejust suiiicient to carburet the air. One end of the shaft 22 extendsoutside and has keyed thereon a lever 23. A rod 24thaving an adjustingturn-buckle 25 is hingedly connected to the end of the lever 23 and tothe movable side 2G of the bellows 27. This bellows is supported on thecarburetor body and has a tube 28 connecting the air tight interior ofthe bellows with the intake manifold 29 at a point posterior to theengine throttle 30.

The sides of the bellows are hinged at 31 and have outwardly extendingserrated arms 32 and which are preferably parallel when the bellows isin an extended position as shown in Figure 1. The spring 311 eX- tendsacross the arms and normally holds the bellows open.

A well known type of auxiliary air valve 35 is placed at the side of thecarbureter, this valve being relied upon to maintain the meteringfunction of the carbureter, regardless of the position of therocker-arm.

The operation of adjusting this earbureter is as follows:

The engine is started and placed under full load until thoroughly heatedand the throttle opened wide. The spring 34 is moved outwardly so as tohold the bellows 27 open, The turn-buckle 25 is then turned so as togradually close the high compression fuel nozzle 15 and open the lowcompression fuel nozzle 14: until a point is reached where knockingoccurs indicating too great a proportion of low compression fuel. Theturn-buckle is then turned in the reverse direction until knockingceases. This fixes the position of point al on the graph.

Starting now with a load on the engine and the throttle nearly closed,the springl 841 is pushed inwardly on the arms 3Q, 33, one notch at atime. The throttle is moved from closed to full open position after eachchange in the position of the spring. At .first the engine will notknock at any position of the throttle, but as the spring is movedinwardly, knocking will begin at partly open throttle. It should then bemoved out\`.:'irdly just far enough to prevent an amlible knock. Thisadjustment lines the point 7) on the graph shown in Fig. 2.

rlhe air valve is adjusted in the ordinary way, as is common with anyfixed-jet, automatic-airvalve, carbureter.

Referring now to the graph shown in Fig. 2, the line (X) shows the curveof a poorly cooled engine having` an eight to one com: pression ratiousing gasoline as fuel A and ethyl alcohol as the high compression fuelB. lt is assumed that with the other adjustments made as indicated, thespring 3lis of such an initial tension as to cause the bellows to openat a manifold pressure of four tenths of an atmosphere as indicated bythe lower end l) of the line to prevent knocking as the throttle isopened. According to this graph, the charge would consist of gasolineonly for all manifold pressures less than four tenths of anatn'iosphere. Once the two ends of the line are known, we can find theproportion of fuel B to the total fuel for a given manifold pressure byrunning a line from the given pressure vertically vuntil it strikestheline (X) and then running horizontally across to the scale at theleft. Thus for a manifold pressure of seven tenths of an atmosphere theproportion of fuel B to the total fuel required is substantially fiftyper: cent.

lt will he understood that the actual comiln'cssion pressure will be aproduct of the compression ratio for that engine which `is a fixedquantity and the density of the charge which is shown in the graph (Fig. 2) as manifold pressure in tenths of atmospheres. hus a manifoldpressure of six tenths of an atmosphere gives in this eight-to-one ratioengine a compression pressure (on an isothermal basis) of six tenthstimes eight or four and eight tenths atmospheres.

The line (Y) is the curve of a well cooled eight-to-one compressionengine using gasoline and ethyl alcohol. as fuels A and B respectively.At full engine compression the lines and (Y) meet at a on the graph,while at low manifold pressures these lines diverge, the line crossingthe Zero line of the high compression fuel at o or tive tenths of anatmosphere. At half an atmosphere and all points below, this engine isrunning entirely on gasoline. This means that this engine operates up totive tenths (.5) times eight, the compression ratio, or four atmospheresbefore any high compres sion fuel is admitted. K

The percentage of high compression fue] in the mixture represented bythe line (Y) may be determined as described for (X) for any givenmanifold pressure by projecting a line vertically until it intersectsthe line (Y) and then horizontally from this intersection to the scaleat the left. The reading on the scale is the corresponding percentage.Thus for seven tenths (.7) of an atmosphere manifold pressure,projecting up to the intersection of the line (Y) and across, we findthe reading on the scale is about thirty-eight per cent, which is thepercentage of high compression fuel in the mixture at this manifoldpressure.

The curve on the same graph represents a siXto-one compression enginemoderately cooled. No high compression fuel is fed for manifoldpressures below siti rtenths of an atmosphere or three and six tenthsatmospheres compression pressure. At full compression or sixatmospheres, the total percentage of high compression fuel required, isapproximately fifty-five. The point a is found from the graphs and (Y)by finding the percentage required for a point c midway between thesecurves corresponding to six atmospheres or a manifold pressure ofseventy-five hundredths of an atmosphere), as previously explained. Atfull load, the high compression fuel forms of the charge.

In the same way the curves and may be used to find the correct operatingcurve for any other engine having a lower compression ratio thaneight-to-one when this engine is operated on this carburetcr and usingthese same fuels, i, e., gasoline and ethyl alcohol.

)Vith a fuel like alcohol which requires approximately one and eighttenths times as much fuel to carburet a given quantity of air, the jetl5 will have to be made larger than the jet 14 to preserve the properbalance and obtain the required condition that at any position of therocker arm the total delivery of the two grades of fuel will be justsutlicient to carburet the air passing through the carbureter.

)While we have shown and described certain embodiments of our invention,it is to be understood that it is capable of many modifications.Changes, therefore, inthe construction and arrangement may be madewithout departing from the spirit and scope of the invention asdisclosed in the appended claims, in which it is our intention to claima'll novelty inherent in our invention as broadly as possible in view ofthe prior art.

What we claim as new, and desire to secure by Letters Patent, is:

1. A carbureter for variable speed, variable load internal combustionengines comprising a mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a source ofhigh compression fuel and means responsive to the load condition of theengine for controlling the flow of fuel from said nozzles to cause theproportion of the high compression fuel in the mixture to .increase asthe compression pressure in the cylinder of the engine is increased.

2. A carbureter for variable speed, variable load internal combustionengines comprising a mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a source ofhigh compression fuel, a throttle valve posterior to said nozzles andmeans for controlling the flow of fuel from said nozzles to cause theproportion of the high compression fuel in the mixture to increase asthe compression pressure in the cylinder ofy the engine is increased.

3. A carburetor for variable speed, variable load internal combustionengines comprising a` mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a source ofhigh compression fuel, a throttle valve posterior to said nozzles andmeans responsive to the suction in the intake manifold beyond saidthrottle for controlling the flow of fuel from said nozzles to cause theproportion of the high compression fuel in the mixture to increase asthe compression pressure in the cylinder of the engine is increased.

4r. A carburetor for variable speed, variable load internal combustionengines comprising a mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a source ofhigh compression fuel and means responsive to the vacuum of the intakemanifold for restricting the flow of fuel from one of the nozzles andincreasing the flow of fuel from the other nozzle as the vacuum in theintake manifold varies.

5. A cabureter for variable speed, variable load internal combustionengines coinprising a mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a. source ofhigh compression fuel and valves responsive to the suction in the intakemanifold for shutting off the flow of fuel from the low compression fuelnozzle and opening Aup the flow of fuel from the high compression nozzleas the vacuum decreases.

6. A carbureter for variable speed, variable load internal combustionengines comprising a mixing tube, a fuel nozzle delivering to saidmixing tube and connected to a source of low compression fuel, a secondfuel nozzle delivering to said mixing tube and connected to a. source ofhigh compression fuel, a bellows operable by the vacuum in the intakemanifold, a spring normally holding said bellows open, and valvesoperably connected to said bellows and operating to close one of saidnozzles and to open the other nozzle as the bellows moves due to changeof pressure in the intake manifold.

7. The method of operating a variable speed, variable load internalcombustion engine consisting of feeding a low compression fuel whichwill knock at full engine compression and simultaneously feedingalcohol, decreasing' the feed of low compression fuel and increasing thefeed of alcohol as the density of the engine charge increases.

8. The method of operating a variable speed, variable load internalcombustion engine consisting of feeding a low compression fuel whichwill knock at full engine compression and simultaneously feedingalcohol, decreasing the feed of low compression fuel and increasing thefeed of alcohol as the vacuum of the .intake manifold decreases.

9. The met-hed of operating a variable speed, variable load internalcombustion engine consisting of feeding a low compression fuel whichwill. knock at full engine compression and simultaneously feeding ahighcompression fuel, decreasing the feed of low compression fuel andincreasing the feed of high compression fuel as the density of theengine charge increases, the amount of said hign compression fuel fedbeing an appreciable part of the total fuel fed.

10. The method of operating a variable speed, variabi load internalcombustion engine consisting of feeding a low compression fuel whichwill knock at full engine compression and simultaneously feeding a highcompression fuel, decreasing the feed of low compression fuel andincreasing the feed of .high compression fuel as the vacuum in theintake manifold decreases, the amount of said high compression fuel fedbeing an appreciable part of the total fuel fed.

li. The method of operating a variable speed, vari able load internalcombustion engine consisting of feeding a low compression fuel whichwill knock at full engine comlill) pression, seid lower compression fuelbeing of high compression fuel as load upon the the only fuel fed inconditions of under-load engine increases t0 the point Where under uponthe engine, simultaneous@7 feeding seid maximum Compression in theengine the feed 10 lonT compression fuel, and n high Compresof lowcompression fuel is cut off and high 5 sion fuel al: medium engine load.positively compression fuel only is fed to the engine.

und simultaneously decreasing,- the feed of FRANK A. HOVARD. lowcompression fuel and increasing the feecl THOMAS R. PARKER.

